@bandinterwebs
Thank you very much for sharing your information.
I think Purdue's IE program is known mostly for its manufacturing/production field. Moreover, the funding is much less than others. In the best case, the funding can cover living expenses+tuition+health (with zero saving)
On the other hand, UIUC is known mostly for its financial engineering program. As you said, UIUC is ranked 15 and Purdue is ranked 8 in overall IE program, however, in terms of OR, it is almost unknown. In terms of funding, UIUC offers almost $700/month more than Purdue. I assume that both urbana and lafayette have similar living expenses.
About chapel hill, yes you are right. Their OM program is ranked 14-18. I think being ranked 14 in business school is harder than being ranked 14 in IE program.
Usually, OM programs are highly OR based and their faculties publish in MS, OR journals.